Solís, 21, joined Birmingham on loan from Girona in January, with a €500,000 loan fee and an €7.5 million option to buy written into the agreement.
That option is now expected to become mandatory, having been tied to the player making at least 11 appearances of 45 minutes or more — a threshold Solís reached across his 13 outings for the club. Birmingham manager Chris Davies confirmed the club were in talks with Girona's parent organisation, City Football Group, over completing the permanent deal.
The interest from Leeds United and Brentford was reported by Girona specialist Ivan Quirós Ruiz, and was subsequently corroborated by South American outlet Win Sports. The timing is significant. Both clubs would prefer to deal with Girona and acquire Solís before Birmingham formally complete the purchase. If that window closes and Birmingham own his registration, the price rises considerably.
Solís impressed Farke directly during an FA Cup fourth-round tie at St Andrew's in February, when he produced a commanding display over 114 minutes — 70 touches, 90 per cent pass accuracy, nine defensive actions and 10 duel wins. He is described by those who have watched him closely as a true destroyer at the base of midfield with the technical quality to circulate the ball under pressure.
Birmingham supporters' trust representative Michael Hatch-Dunn made the club's stance plain.
"Unless they want to come in for £50 million, it's just not going to happen. Realistically, unless they come in and say they really, really want him and offer us £20 million, it's just not going to happen. I fully expect Jhon Solís to be a Blues player next season and he'll be trying to bring us up."
Leeds are currently assessing their midfield depth following a season in which Ethan Ampadu has carried a disproportionate burden at the base of the squad. Brentford's interest fits their established model of identifying value in underexposed markets. Both clubs will face the same reality this summer — Birmingham, if they complete the purchase, hold the cards.