Farmstead Gleaner
Artifact Creature — Scarecrow
This creature doesn't untap during your untap step.
, 
: Put a +1/+1 counter on this creature. ( is the untap symbol.)
When it finishes the harvest, you'll have nowhere to hide.
Josh Hass
Modern Horizons (MH1)
• #222Rulings
Untapping an attacking creature doesn’t remove it from combat.
(wotc • 2019-06-14)
The untap symbol, {Q}, functions the same as the tap symbol, only mirrored. You can’t pay the {Q} cost if Farmstead Gleaner is already untapped, and you must have controlled the creature continuously since your most recent turn began in order to pay {Q}.
(wotc • 2019-06-14)
Rulings
Untapping an attacking creature doesn’t remove it from combat.
(wotc • 2019-06-14)
The untap symbol, {Q}, functions the same as the tap symbol, only mirrored. You can’t pay the {Q} cost if Farmstead Gleaner is already untapped, and you must have controlled the creature continuously since your most recent turn began in order to pay {Q}.
(wotc • 2019-06-14)