TP-Link has been alleged to have National Security concerns due to its ties to China.

You can read for yourself but when this was in the news ~1 year ago I looked into it. To me it seems like a combination of a smear campaign started by Netgear and bad actors from the Republican Party within the government.

Edit: This is a pretty good write up that explains it without straying too far into opinion.

Tp link problems with updates, possible back door, charges you to make basic config to your router as they force you into yearly memberships. The router itself is solid.....

I am also interested in knowing, got a tp link 4G router currently and have been wondering about getting a 5G router sometime. UK so doesnt matter if its banned in the US.