Many people render video through different pieces of software, so maintaining the original video quality through each step is important until the media is ready to be lossy encoded. For whatever reason, Premiere cant do this even when they support codecs that literally have a lossless option (h264, h265).
There is a 3rd party codec that can export to lossless AVI but its old and hasnt been updated in years and doesnt handle media that are HDR or color bit depths higher than 8 bit. 264 and 265 can though.
Please for the love of god add a lossless option to Premiere exports for h264 and h265 since these codecs Premiere leverages literally can do lossless.