Disc brakes too tight after pad replacement
Deore disc brakes (and most others) use a spring to apply pressure to the pads which helps the pistons and pads retract when you release the brakes (the primary return mechanism for the hydraulic system is a spring in the piston assembly in the lever, however as this only acts on the pistons the pad return spring is responsible for separating the pads from the rotor). Often a pad return spring will come with the new pads (an example listing from CRC) but if not you can reuse the old spring as long as it is undamaged.

If you don't recall installing the spring when you changed the pads it may have fallen out and gotten lost, or it remained in the caliper when you removed the old pads and is now sitting underneath the new pads. When installing the new pads for this style of brake the prongs of the spring should sit either side of the friction material and rest on the face of the metal backing plate closest to the rotor (~5:30 in the linked video shows the process). The holes for the retention pin should line up as well.