The Bucks, who slipped to third, were dealt a damaging 2-0 home defeat by fourth-placed Darlaston Town (1874) in the West Midlands Division One North.
The result came a couple of days after the club announced boss Brown, who joined the club in June 2021, had stepped down with immediate effect.
Telford Ladies' search to appoint his successor is already under way, but a replacement has not yet been confirmed.
The defeat was Telford's fourth in 12 league games this term and saw the Bucks slip up as high-flying county rivals Shrewsbury Town Women and Shifnal Town Ladies won away to strengthen their positions.
Kelly Shirley and Emily Smith scored the goals for visitors Darlaston to condemn the home side.
Meanwhile, both Shifnal and Shrewsbury kicked off their 2022 with victories away from home to extend brilliant unbeaten league runs.
Shifnal remain clear of the pack by just a single point from Salop after a hard-fought 3-1 win at Coventry City.
Victory came courtesy of the contest's star performer, as Rebecca-lee Bown struck a hat-trick for the visitors to maintain their slender lead in the title race – albeit having played a game more than rivals Shrewsbury.
Coventry had Letitia Markham sent off for two yellow cards.
To add further drama to the battle between the Shropshire duo, Shifnal and Shrewsbury now both share the same goal difference of +34.
The pair meet in a clash that will almost certainly play a significant part in the destination of the league trophy at Shrewsbury on February 27.
Shrewsbury remained on Shifnal's coattails with a comfortable 4-1 win at bottom side Wyrley.
Tom Peevor's side shared around the goals, as Maddie Jones, Paris Schofield, Shannon McShane and Zoe Child struck in Staffordshire.
Attention now turns to a big county derby on Sunday, as the managerless Bucks welcome Shrewsbury to TCAT (2pm).
Shifnal are on their home patch, as they tackle Walsall at the Acoustafoam Stadium.
In the National League One Midlands, Wem Town's fine recent progress was stunted with a tight 1-0 defeat on the road at runaway leaders Doncaster Belles.
Jasmine Saxon struck a 19th-minute winner for the hosts, managed by former Rovers defender Andy Butler, on an afternoon brave Wem battled throughout.
Visiting goalkeeper Asher Oddy impressed, keeping the leaders at bay. Doncaster now head the charts by five points, Wem are eighth, with games in hand on sides above them.
David Healey's side are at home on Sunday, as they welcome Solihull Moors, in ninth, to Butler Sports Centre.
Bottom side The New Saints Women are still to kickstart their 2022 due to playing restrictions in Wales, but they resume action with a Genero Adran Trophy quarter-final tie at Park Hall against second-bottom Port Talbot.
Following that, their Adrian Premier campaign is pencilled to restart on the road at Port Talbot on February 13.