Will I face problems re-entering Thailand after multiple 60-day visas this year?

No you'll be fine

500 thb/ day if overstay!..

The secret is to stay away as long as possible from the date of exit to another

I left Thailand in March this year, stayed 90 days on visa exempt and came back in May for another 90 days visa exempt

I could try my luck again, but it is said that we have 180 days in total in an year calendar, so better not trying it

Idk what's your business in Thailand but try to stay at least on the 180 days a year and stay at least one week or 15 days away from Thailand. If you do a visa run, that is, you spend a weekend or less in a country and come back, the officers think you're working illegally or have some shady business in the country

Good luck hope it helps

Depends if the IO has had his/her Leo

Nobody knows....

While it's up to the Immigration officer, you're clearly not living here with the gaps in travel which is what they often look for.

I've done the same 45 visa on arrival from jan local extention 30 days and a boarder run 30 days up to May. Came back for 21 days in August got a tug . Told to many stamps and extention over the last 5 years through so I think your be fine . Got a new passport now back for 21 days no problem. But iam doing my retirement visa in January its much easier than the worry now.

No issues

If you're saying you had 60 day VISAs both times and you are entering again for the 3rd time this year by Air then no there will be no problem. If you follow the rules and don't over stay your VISA you are good. I've been to Thailand 5 times in 2 years with no issues.

The only person that can answer that question is the immigration officer you'll be standing in front of when you try to enter Thailand. Each officer has their own discretion as to whether or not you will be allowed to enter Thailand.