Ok!

I have a Beta HX115 that I have been learning to fly / tune on.  I'm currently using Joshua Bardwells rates & PID.

Issue:  After takeoff, everything will perform normally for typically 15-30 seconds before, what for lack of better understanding, seems to be my roll rate changing dramatically.  Typically it would take a few tenths of a second to complete an entire roll when throwing the stick all the way to either side.  Instead, what happens when this anomaly rears its head ( which occurs mid flight, right after takeoff is perfectly fine, and sometimes throwing the quad around a couple of quick pitch loops magically solves the problem.. for a little bit ), is that suddenly when I move the roll stick its INCREDIBLY mushy and unresponsive.   Throwing the stick all the way right or left for a roll results in a roll that takes well over a second.. close to 2 seconds most often to complete.  

Any advice where to start replacing items, changing tune would be greatly appreciated!!
Mind this is my first quad, so it has taken somewhat of a beating thus far.  I have no doubt of the possibility that I've broken hardware or made mistakes in software... Though at this point, the changes I've made in the software are nearly non-existent with the exception of flashing betflight 4.1.1 and using JB's rates/PID's.

Thanks!

This will be a difficult problem to solve. I initially thought it might be your lipo packs but you mentioned that you can get it back to normal if you do some quick pitch loops. It is not likely you rates or PIDs. If I have to guess, it sounds like a hardware problem. Maybe the gyro is not registering the correct rotation. Maybe others might have some insights.

I agree with Voodoo that this is almost certainly a hardware fault of some sort. Because it's so random and it returns back to normal mid-flight, it can't really be anything else. Betaflight has no mechanism that dynamically shifts rates like that and if it was some kind of bug in Betaflight we would have seen other reports of the same.

Blackbox logs would definitely help show any potential anomolies with the gyro, assuming your flight controller has Blackbox logging capabilities. If you are able to get a log of a flight where the issues occurs and post it back here, someone can take a look to see if they can make any sense of it, but I think ultimately you are probably going to end up having to replace the FC.

Still in the learning curve and blackbox logging is next on my priorities.
I did find the problem and it's probably the last place I would have looked. The Taranis Qx7s. I just got ahold of another quad, and during setup in the receiver tab I noticed my roll doing odd things. Sometimes it would go up and snap back just like the ailerons were doing, and then all of the sudden when i'd let the aileron snap back to center the value would slowly return back to mid value. Sometimes it was slightly off then I managed to get video of it returning SUPER slow... not that the video really helps, but point is, I disassembled the transmitter, and found the chip above the bearing/magnet on the hall effect gimbal to have an ever so slightly small amount of.. crud? that was giving me the slightest continuity between two wires in the solder side of the through holes for the roll board.

I did do multiple things here though, and I cant say that was the actual cause because I didn't test after each part. I also cleaned the bearing/magnet which appeared to have a slight bit of metal dust. I unplugged and reseated the (jst?) plug that goes from the sensor to the main board and lastly wiped down the sensor and reseated ( didn't check for alignment when I removed - just reseated in proper spot ).

Back in betaflight and everything looks great, I can't replicate the problem any longer.

Hopefully this helps someone else one day when they run into this! Thanks for the replies

Good troubleshooting.