I also have had similar behaviour before now when running multiple tests in sequence certain ones failed whereas if I ran the tests individually the tests passed.
This issue was nearly always due to resourcing and latency when I had this issue.
As @HimanshuTayal suggests - you need to review your logs but maybe provide a bit more info.
Did the same testcases fail each time or were the failing testcases different?
The reason for the failing testcases - are they failing on particular test steps? e.g. JDBC request to retrieve a large number of records?
The latency could be local to you (your laptop resourcing) or server end resourcing (threading/memory/CPU resourcing).
To 'fix' my problem, I added some waits via the 'Delay' test step at appropriate places (within my tests within the project) just to slow things down a little (based on the results of my analysis of the failures) and this resolved my problem.
I also checked that I wasn't running the tests in parallel but in sequence which can cause different tests to fail each run depending on the available resourcing for the endpoint I was hitting.
if this helped answer the post, could you please mark it as 'solved'? Also if you consider whether the title of your post is relevant? Perhaps if the post is solved, it might make sense to update the Subject header field of the post to something more descriptive? This will help people when searching for problems. Ta