I presume that you have not yet moved to AIB?
If not, you can fix at 4.6% with Ulster Bank until Dec 2025.
But as that takes you beyond the maturity date, I don't think that they will let you fix.
So you are currently paying 5.35% or .75% more than you would be paying if you fixed.
0.75% @ €39,000 = €300 per annum.
It will be less as you are paying down the capital, so about €200 extra in the next 12 months.
And if ECB rates fall, the would be even less.
No need to worry about it.
Brendan