Do you have any existing conditions that would cause this OP? What was said when you were discharged and what further investigations are pending?
If this is happening now and you're concerned and symptomatic at the HR you're at then call 111 and seek medical advice from them and ask your GP for further investigation on Monday. It is highly unlikely you would have been discharged if there were any immediate cause for concern or abnormality on your ECG etc.
I have a condition called POTS and am often tachycardic at rest and definitely have a similar HR when I stand. I believe it is unfortunately becoming more prevalent in post covid patients, which is a shame.
A high HR can be worrying and checking it continuously can make things more anxiety inducing. Whether it needs treating depends on the cause and duration, whether you're experiencing any symptoms with it. See what 111 say, be sure to stay very well hydrated and practice deep measured breathing which may help in the short term to lower the HR.