The following are the most common reported 'triggers' for AF among people on health fora:
a. alcohol;
b. poor sleep;
c. anxiety, often about the palpitations and other symptoms they feel...so a vicious cycle;
d. low or high electrolytes in their cellular structures and/or in their blood;
e. dehydration, often related to d above, or excessive caffeine or alcohol consumption, or diarrhea and vomiting;
f. mitral valve problems, mostly prolapse;
g. pericarditis, sometimes linked to vaccines. or myocarditis, ditto, or due to poor oral hygiene and gum disease;
h. untreated sleep apnea (central, obstructive, or 'complex', which involves both in one patient);
j. poor bowel habits, gut health, biome messed up, straining, gas, and stomach distension (ingesting too much at one time;
k. ischemia, especially of the heart;
m. over-training, or training when you ought to have had a rest day (elevated HR first thing when waking is an indicator).
n. GERD or reflux disease, or just the odd case of indigestion after a meal, often due to red wine or spirits consumed at the same gathering, and this is worse as you get older;
p. Histaminic or allergic response to something, whether breathed in, ingested, or introduced through the skin pores or through lesions. This includes prescribed medications and voluntary supplementation.
q. dysautonomia (you might as well google it now and get it over with);
r. stressors and worry/ruminating excessively over 'issues' that are looming, often intractable, and that make you feel defeated or overwhelmed; and
s. anything else that reliably sends you into arrhythmia.

This is just a guess (we don't know each other, and I'm the furthest thing away from being a medical professional you'll ever meet), but if you have IBS, you have maybe one or more other 'things going on' that you're aware of and that is being monitored if not treated already, and ......AND....you have some measurable systemic inflammation. Inflammation is nasty if left unmanaged and chronic because it damages blood vessel linings, makes deposition of plaque much more likely and pervasive, and it can then lead to cardiac disorders, hypertension, and the body wanting to just make it all stop....usually by mounting even stronger defense reactions. I know this because I am married to a woman who is really messed up that way. I won't go into it, but she's a walking pharmacy, and some of those prescriptions can't be doing her a whole helluva lot of good. But...I'm not her doctor.