It could be an intermediate sector between 125.075 (high) and 133.775 (super high). It may also be that 133.775 is now super high above 132.825, and the new sector is super high above 125.075.
I would suggest listening to where flights get handed to, that might give some clues. It’s probably simulcasting a UHF frequency that could point to the existing sectors as well.
It was discussed the other night on a Facebook group that the frequency will be filling a gap of poor radio coverage in the area from Zanesville, Ohio to the Charleston, West Virginia.
Other frequencies / sectors that flights on the 135.425 MHz are being handed off to are the following ones I have heard so far
135.800 MHz Indy Center Sector 78 Springfield (High)
132.825 MHz Indy Center Sector 87 Appleton (High)
123.775 MHz Indy Center Sector 93 Dacos (Ultra High)
120.275 MHz Indy Center Sector 95 Henderson (Ultra High)
134.700 MHz Indy Center Sector 76 Batesville (Ultra High)
135.135 MHz Indy Center Sector 79 Bobcat (High)
119.875 MHz Cleveland Center Sector 48 Ravenna (High)
125.425 MHz Cleveland Center Sector 66 Bellaire (High)