FYI this issue is crossposted on Reddit here
When I go to chrome://settings/cookies/detail?site=google.com&search=cookie and look at the google.com entry it says 13 cookies and expanding to show the detail it displays the following which are the cookies that I believe WERE at one point being deleted automatically and in the process leaving the 2FA cookies untouched:
1P_JAR
APISID
HSID
NID
SAPISID
SID
SIDCC
SSID
__Secure-3PAPISID
__Secure-3PSID
__Secure-APISID
__Secure-HSID
__Secure-SSID
In Firefox I use a third party exentsion “Forget Me Not” to remove “sid@*.google.com” cookies which forces a logout from Gmail but leaves the 2FA cookies untouched.