I don't think this announcement is as juicy or controversial as you were hoping. It appears this was developed jointly with Grafana Labs as a part of a longer term partnership: https://grafana.com/blog/2020/12/15/announcing-amazon-manage...
This is a thumb up for open source the development model.
IMHO I will be more worried that a good piece of open source software is only commercialized by one company, by all accounts, that leaves a lot of risks unaddressed.
Lastly, to anyone claim that this hurts their feeling, I cannot help feel very surprised that one with some ideas of the business cycle and Amazon's (or any big corporations) track record, would not anticipate this. Personally, I am surprised that AWS have not started this in 2014, I guess they have been so successful that they probably cannot hire fast enough to get started.
I know one relates to API compatibility, but those companies never end to surprise me.
[1] https://techcrunch.com/2019/01/09/aws-gives-open-source-the-...