2017 WRX lag in acceleration?

Sound like your issue causes a misfire under heavy acceleration. Any sort of intermitent engine issue is going to be exacerbated by heat, but if you let it keep going on, it will more than likely start to happen all the time or a component will fully stop working. If it throws a CEL and/or code, get it scanned and start there. If not, spark plugs and coil packs are a good place to start.

I had a similar issue on my 2008 WRX, not the same engine but similar coil-on-plug ignition. I replaced coils and plugs with OEM coils and NGK plugs and it fixed it for me, looks like one of my plugs had a cracked insulation but everything was getting old anyways. Boost usually peaks around 3000rpm and tapers off afterwards. My theory is that the high pressure exposes any weakness in the ignition.

You should also check the intake plumbing going from the MAF sensor to the turbo, and then the turbo to the intercooler. If anything has come loose or sprung a leak, that would also not make your car very happy under boost. A shop would probably start by testing your intake tract with a smoke machine. How many miles? Have you had a walnut blasting service yet? Hope this helps!