04562-12010 "Dam Kit, Back Window Glass".
Still available for about $45. It may be a length of generic molding as it's listed for multiple Toyota models from the 90s. The MR2 specific part above appears to be discontinued.
The rear window has 3 separate weather strips, not including the one that goes between the roof and the big U-shaped rear window trim that comes apart. The weatherstrips that touch the rear glass by the high mount center brake light are actually two pieces.
Here's an exploded parts diagram. The top one is my reproduction sold on eBay or available directly through me via Facebook or Instagram (@nickmr2). The bottom molding 75575-17010 is now discontinued. I may have it remade.