Present perfect tense with definite date

[ctying]

As far as I understand, present perfect tense should not be used with an event that has a definite time. Is the following sentence grammatically correct?

The banking relationship has been established since 1 Jan 2022.

[Joe]

The banking relationship has been established since 1 Jan 2022.

Your sentence is possible (correct) though it might be easier to say:
The banking relationship has existed since 1 Jan 2022.
The banking relationship was established on 1 Jan 2022.

Present Perfect with...
for a period of time
since a point in past time

Look at these example sentences using for and since with the Present Perfect tense:

I have been here for twenty minutes.
I have been here since 9 o'clock.
John hasn't called for six months.
John hasn't called since February.
He has worked in New York for a long time.
He has worked in New York since he left school.

https://www.englishclub.com/grammar/ver ... erfect.htm