There is definitely a problem in that, like all bosses, you need to minion-screen them or else they will just go down to concentrated fire; but if you give them too many rounds of unimpeded eye rays on the party PCs are going to die without feeling like they had a lot of real agency in the situation. In particular because of how many of the eye rays are the on the 'avoid or die' end of the 'save or suck' spectrum; and also because of how many things 5e makes into spells/how much a well-placed concentration spell is the biggest situation-changer and how anti-magic interacts with that. There's a real fine line between giving the party a good fight and making it feel like an unfair fight -- especially retroactively after a TPK or near TPK (perhaps with perma-dead PCs).

That said, it's not wildly worse than a couple of illithids, or a dragon and a giant and minions, or a bunch of NPCs (built as PCs or the MM equivalents) also with minion support. They all run a fine line between 'too easy' and 'unfair-feeling TPK.'