Should Soulslikes be understood as a subset of Metroidvanias? I think the issue gets a little muddied because the Metroid Prime franchise went in a very different direction as far as adapting that formula to three dimensions, but on the one hand modern MVs put a lot more emphasis on precision platforming1 and timing and pattern recognition in big, difficult boss fights, and on the other hand, many modern MVs (Hollow Knight of course, from what I hear also Blasphemous and many others) are clearly also SLs.
And frankly, I'm not even 100% sure the Prime games should be considered Metroidvanias proper2, but that's a whole other discussion I'm not prepared to really engage right now.
The "Soulslike" formula (which, like "Metroidvania" or "Roguelike" or any of these types of subgenre labels, is of course a category with fuzzy and shifting boundaries) just doesn't seem to me to have any significant incompatibilities with the "Metroidvania" formula, only additions to it, if that makes sense.
1which Prime, of course, obviously wasn't in a position to do, because it was blazing the trail for translating recognizably Metroid-feeling platforming from 2D to 3D without 90% of the player base immediately bouncing off! neither this nor anything else I ever post constitutes disparagement or criticism of the Metroid Prime franchise, nor will I brook any such in the comments.
2see 1, this is not a criticism or disparagement.