Before we can give you decent advice it would help to know a lot more details:
1. What kinds of sports and motion subject and where are they - for example, there is a big difference between shooting sports on a well-lit field, compared to do so in a relatively dimly-lit hall.
2. What lenses do you use now. The body does not work on its own, it is a component on a system with the lenses. One thing that strikes me immediately is that you are looking at a full-frame body, but unless you are currently using full frame (EF as opposed to EF-S) lenses, then the camera will automatically go into crop sensor mode to match the area projected by the EF-S lenses reducing your sensor capacity by a factor of 2.56, so reducing your effective capacity from 26MP, to about 10.
3. This takes us to what you will produce. If you are shooting to produce for social media, where the images are dramatically reduced, then this may not be a problem, but otherwise you may want to consider an alternative such as either getting FF RF (as opposed to RF-S) lenses, or going for an APS-C camera - which is the same sensor size as your T7. Right now those would be the R7, R8, and R10. Of the three the R7 is the most expensive, but offers the best performance for action as it has In-Body Image Stabilization (IBIS), a bigger battery and better build. You should research the features of each and decide if one of them offers value in terms of benefits where the features match the benefits you actually need.
My previous post was in response to the information given in this thread, and I just found a previous thread where you give more details - really this should have been part of that thread, but we are where we are...
Some of your issues may well be the limitations of the current gear - the T7 has a relatively slow frame-rate, and the 75-300 lens is arguably one of Canon's worst optics. However, it may also be a skills issue, given that you are referring to exposure issues, some of which come with the lens, but others are likely to be relating to technique.
OK, so to answer some of my own questions from what I understand from your other thread.
I gather that you want a system capable of shooting sport in relatively poor light.
Given that you apparently have the EF-S 18-55 kit lens for an APS-C crop camera, you would be mis-matching the current lens with the FF body of an RP Full-Frame body and using it with the RP will reduce the MP potential of that sensor from 26MP to about 10MP when it is using that lens.
The other lens, the EF 75-300 which, while a FF lens (and thus using the 26MP), is extremely mediocre.
You will not gain the full potential of a camera upgrade to the RP without the combination of that body with a reasonably fast FF lens. Given you have a budget of $1,000 or so, that is not likely to be sufficient to provide both a good lens and good body.
Please read the enclosed post and consider what you need to do if you want to upgrade. Don't look for bargains that are not going to serve you well, and I suspect the RP is one of those for the reasons given above.
Given your budget, I would suggest you might want to consider several options to proceed.
a) If you want to move into the R-series world, consider holding back and saving more to be able to afford a matching body and RF-series lens. In the long run this could well provide you with the best results.
b) If you want to keep the T7 body and accept its shortcomings, you could get a faster and better quality EF lens. This could be something like a Sigma 100-400 lens for an EF mount or go for a prime lens that has a faster aperture. If you get a decent lens you can adapt it to an R-series body via the EF-RF adapter.
c) Get a new body and get a EF-RF adapter to use your current lenses with the new body. In that case I would suggest one of the APS-C bodies like the R10, R50 or R100, which offer things like face and eye tracking and you will get the full use of the sensor as your kit lens will match that sensor format. When you can afford to, you can then invest in RF-S glass to complete the upgrade process.
c) Finally, consider sticking with the DSLR platform (they are still great cameras) but look for something higher end, like the 80D or 90D. They are far superior to the T6, and consider if you can afford a better optic second-hand or from Canon's refurbished offerings.
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