How often are you watering?

The leaf issue is probably due to sunburn, as you moved it to a sunnier location (was the move gradual?).

Hoyas love well-draining mixes, such as orchid mix. They are not cacti/succulents, and prefer not to be treated as such.

I assume that your hoya is Hoya obovata. I have mine in an orchid bark mix, water weekly, and use clips to train on a trellis. It is one that likes it's growth tips (the vine part) pointed up. I clip mine on a trellis, so that the new growth is always pointed up, or at least to one side or the other.

i wonder if that's an overwatering/poor drainage issue.

i have an obovata and it's planted in a bark/pumice mix. if it's in a cactus mix (sand, soil, etc.) it's probably not getting good drainage. my understanding is obovatas (roots) prefer to be drier between watering.

you'll probably have to look at the roots; check for root rot. if they are okay (not mushy), you might want to repot (remove all soil) into a bark mixture - you could use gubler orchid mixture - home depot and maybe lowe's carries it.

i would also remove all of the damaged leaves.

this is a perspective from a newbie to hoyas, but a decently experienced gardener.

Thank you both very much for your replies It is indeed an obovata. I'll put it in a bark mixture and check for any rot. I know it's not a cactus or succulent but I read they need really good draining soil and it's what I had on hand. I appreciate your help so much!

I'll also look into clipping it up somehow. Do you happen to have any pictures you can share of your set up?

Oh, and will the plant adjust to the light if it does have sunburn or should I move it again?

You can slowly acclimate it to brighter conditions. Move it to a sunny location for 3 hours a day for one week. The next week, keep it in the sunnier location for 6 hours a day. The following week, it can permanently stay. Alternatively, you can put sheer curtains over the window you plan to keep it in.

Here are a couple of examples of how I trellis/hang my hoyas:

Hoya ruthiae, clipped to trellis in hanging pot:

Hoya australis 'Silver Creek', clipped to hanging pot:

Hoya calycina, clipped to hanging pot:

Hoya sp. Ban Ngon Ngoy, clipped to hanging pot:

Hoya dolichosparte, clipped to hanging pot (sunburnt leaves):

Hoya darwinii, clipped to trellis:

Eriostemma (hoya relative) combo pot (cv. Ruthie, cv. Kalani, cv. Optimistic), clipoed to trellis:

Hoya imperialis, clipped to trellis:

Oh those pictures are great and very helpful, beautiful plants!