This is happening to my hoya compacta lately as well, I keep most of my house plants outside for the summer and I think mine got a little too much water and a little too much sun. Try watering less, or make a well-draining soil mix with perlite, leca, orchid bark, and potting mix! Hoyas can be very dramatic and picky with their placement, try moving it a little more of a shaded spot, where it gets more indirect light than direct. Hope this helps! Good luck!

I didn't think that it could be a too-much-light problem but that might make sense! It seems to have started when I moved it closer to the window a few months back. It's already in gritty mix and I let it dry pretty well between waterings so I'm hoping that's not the issue.

I'll try moving back farther from the window and see if that helps. I also gave it a good drench with neem oil today just to be safe. Thank you!

that does look like light damage mine have similar discoloration

I did move it from the window and it seems to be doing a little better, although it's hard to tell if the discoloration has stopped since it's such a slow grower! I will keep an eye on it and post any updates in the future :) Thank you for all your help!