There is an even better place to report adverse reactions to the Covid vaccines.
https://wonder.cdc.gov/vaers.html

Some people have complained that, "It doesn't do any good to report." Let's begin with this premise - The CDC and vaccine manufacturers cannot fix what they don't know. They do not monitor the newspapers, Connect, or any social media for their reports - they use VAERS.

Maybe I can explain a little about how it works. All adverse reports are tabulated, those that are life-threatening are followed up quickly - IF the reporter includes complete contact information. The remainder go into a "matrix" that rates them by severity & frequency (how often per 100 or 1000 doses of a vaccine.) The most serious and common are then studied, and the manufacturers may be asked to do further testing, then either modify and/or remove the drug temporarily or permanently.

As for the quality of reporting - that is up to the reporter. I submitted a VAERS report after an adverse reaction to a different vaccine, not Covid, complete with my contact info. It happened to be an issue they were studying, so I got a phone call to follow up and did a phone interview. It turned out this was a common problem due to an error in administration of the injection, and the instructions were to health providers were revised.

If you have A-fib that you believe is due to the Covid vaccine, it is not too late to report it.