For sources, it stops at 500 individual sources unlike bases/portals in 1.8.10 where it stopped at 500 different types.
Kind of restrictive but not the end of the world

Sell source tiles you do not need - the game has a technical limit on the amount of different tiles in your inventory, to prevent out-of-memory errors, lags and very large save files.
As ZiHeLL has already mentioned, 500 different tiles is the limit.