The two clubs conducted late business in the summer transfer window, as the Lilywhites sent Argentina midfielder Giovani Lo Celso back to his former club on a permanent deal.
Betis and Tottenham had previously negotiated Lo Celso's move to North London in 2020, but the former Paris Saint-Germain midfielder ultimately failed to make the grade in the Premier League.
While discussing the Lo Celso deal, Tottenham and Betis also held talks over USA international Cardoso, whom Tottenham were reported to have struck a peculiar transfer deal for.
As confirmed by Betis president Angel Haro - in quotes attributed to The Telegraph - Tottenham successfully negotiated a first refusal option for the 22-year-old, which has reportedly been set at €25m (£21.1m).
Tottenham 'have two weeks' to trigger Cardoso option
However, the Lilywhites' move for Cardoso is not set in stone just yet, as Haro confirmed that other sides are still in the running, saying: "Johnny is a player who is of interest not only to Tottenham, but to many other teams.
"[He] has great potential and in this case, within the Gio operation, they asked us for an option to buy for a value that was important and interesting for us and we did give them that option."
Rather than signing Cardoso on loan for the 2024-25 season and retaining an option or obligation to make his stay permanent, the report adds that Tottenham have been given a two-week window in 2025 to activate their clause.
Should Tottenham fail to do so, Ange Postecoglou's side could still negotiate a different agreement with Betis, but they would have to fend off interest from other teams and would also hold less power in negotiations.
Who is Tottenham target Johnny Cardoso?
Born in the United States to Brazilian parents in 2001, Cardoso began his footballing career in South America with Internacional, breaking into the first XI as a teenager and making 144 appearances in total
The 22-year-old became a trusted fulcrum in the centre of the park for the Brasileiro side, who sold him to Betis in January for just €6m (£5.1m), and he quickly adapted to life in La Liga.
Under the wing of former Manchester City manager Manuel Pellegrini, Cardoso scored one goal and set up two more in 19 appearances in his first half-season at Betis, starting 15 La Liga matches in a defensive midfield role.
While he was eligible to represent Brazil, Cardoso pledged allegiance to the United States national team and has won 15 caps for the Yanks, including two appearances at this year's Copa America.
The midfielder is contracted to Betis until 2029 but has failed to start any of their first three games of the 2024-25 La Liga season, coming on as a second-half substitute in last weekend's 2-0 loss to Real Madrid.