VO2 Max calculation issue

How did you determine your Max HR is 140?

PS: I am drilling into this question because incorrect input(s) is the main cause of inaccurate metrics. Max HR is the cornerstone of these inputs, although it is not obvious to determine its value.

170 

I've done a VO2 Max test with my doctor with mask and so on.

I can confirm that my MO2 Max is going down slowly, I ran yesterday up to zone 4 and still 70.

I guess I'll have a more realistic number within 2 or 3 months....unbelievable Garmin!

Is there any way to raise my post to Garmin to unsure they read it to apply correction?

I cannot believe I'm the only one to have this issue.

Garmin employees rarely read posts here. Some manage to get attention via forum personal messages.

The preferred route is to contact Garmin support in your country. 

I am running out of ideas about why your VO2 Max is so off. 
You could still do a watch backup and do a factory reset. Then do not connect the watch to your phone or your Garmin account, input your Max HR, weight and age, use a chest strap and use it a few days. You will get a fresh new VO2 Max. If the new value is much better, continue using the watch for a couple of weeks before reconnecting it. If not, restore the backup: historical data is not the issue.