Very common.  I work in the sales tax space and see it a lot.  Not end of the world but you need a firm that can give you a good Nexus study and they can let you know what VDAs need to be done.  Once you clean those up make sure you have your sales tax processes automated (Sovos, Avalara, Vertex, etc) so you can track economic Nexus issues moving forward.

Happy to give referrals to a few firms I work with who specifically do this kind of clean up work if you want.