Is a buy offer @ 2.2 x ARR a good offer?

Counteroffer with x3.5 - never go below 3.
x2.2 is simply too low unless there is a reason on your side for it (you are losing customers fast, the market is dying, you need to monetize it quickly).
Growing competition can mean only that there is space to grow.
This increases your value, not decreases.
The average multiple is 3-6 now (depending on the age of SAAS, market, growth, brand, and a few more factors). It can go much higher, but it also can go lower (there are so many variables that affect this).

Just do a counteroffer and see what happens.
If you really want to sell and you won't get what you want from the offerer, just list your SAAS on SAAS acquisition marketplaces.
Sure, his offer is easy to take, but clearly, he is trying to benefit from the simplicity of it, while getting it at half price.

Just a note - this is advice for a regular SAAS. Your market is unknown, the same goes for what you offer, and what is value given. This can change everything really.

I’d start at 10x and negotiate down until the x you’re willing to accept.

You never know and it shows you highly value your startup.

Hard to say. Do you see your company surviving more than 2 years with the same monthly revenue?

What’s the company? Url?

If you’re serious about selling, put it on microacquire and see if you get comparable offers. You can use those offers to negotiate the current offer as well.

Depending on your growth curve, revenue, profit, support demands, industry, etc… a 2.2 multiple could be great or horrible.

No

It sounds very much on the low side.

I don't know about indie hacker businesses specifically, but this seems to be comparable to the revenue to market cap ratio that's used for startups and public companies. In that metric, 2.2 is very low for SaaS businesses afaik. Current multiples seem to be between 12 and 16x ( see https://www.saas-capital.com/blog-posts/2021-private-saas-company-valuations/ ) even tho they have been lower in the past.