MemAvailable shows the amount of memory the kernel can supply to a process when asked - is a request exceeds this value, then an Out-Of-Memory event will occur, and a process may be killed.
Swap memory is also used more aggressively in 14.1 - idle pages from memory will be moved to swap by the kernel in a way that did not occur in earlier versions, so swap is generally high.
If swap is high and MemAvailable is stable, then there is unlikely to be a problem.
If swap is high and MemAvailable is continually decreasing, then there is likely to be a problem.
If MemAvailable is low (I'd suggest under 300Mb), then I'd suggest looking at the memory allocated to tmm to see if some can be moved back to the linux host via the provisioning settings. However, with a 2-core vCMP guest (3.5Gb memory) this may still be constrained.