Troubles opening TCP ports in GitHub actions (recent development)

[aaime]

A test that we had running for years has recently (last week or two) started failing, reporting inability to open tcp ports, e.g.:

2021-04-16T09:42:17.9471328Z [ERROR] Tests run: 5, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 15.496 s <<< FAILURE! - in org.geotools.data.h2.H2DataStoreFactoryTest
2021-04-16T09:42:17.9473048Z [ERROR] testTCP(org.geotools.data.h2.H2DataStoreFactoryTest)  Time elapsed: 15.461 s  <<< ERROR!
2021-04-16T09:42:17.9475510Z org.h2.jdbc.JdbcSQLException: Exception opening port H2 TCP Server (tcp://10.1.0.88:49153) (port may be in use), cause: timeout [90061-119]
2021-04-16T09:42:17.9477672Z 	at org.geotools.data.h2.H2DataStoreFactoryTest.testTCP(H2DataStoreFactoryTest.java:126)
2021-04-16T09:42:17.9479350Z 

I've been looking at a potential smoking gun in the recent code changes, so far finding none.
Also tried to apply the suggestions in this ticket: #1187

Wondering if there could be any recent change in the hosting enviroment that could explain the failure?