Bear in mind that these kinds of social psych experiments have some of the worst reproducibility is science . . . they're the kind of thing people love to talk about, but which often don't hold up.

. . . basically, with findings like these, until you've seen them reproduced by other investigators, don't go off too far into the weeds in interpretation, because these are pretty soft findings and the authors themselves offer other possible interpretations

>Although we observed instances of feeling appreciated when they spontaneously arose in daily life, it is unclear what the effects would be if people were explicitly instructed to express their feelings of appreciation toward their partner. It is possible that these increased opportunities to perceive their partner’s appreciative feelings may enhance the effect upon prosocial motivation.
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>Alternatively, it is also possible that intentional expressions of feeling appreciative may appear contrived and therefore less authentic, which may weaken the potency of the message. Future research would benefit from an experimental paradigm to assess if intentional expressions of feeling appreciative can buffer prosocial motivation for avoidantly attached individuals.

All in all, I wouldn't rank this as anything beyond "interesting"

See:

Wiggins, Bradford J., and Cody D. Christopherson. "The replication crisis in psychology: An overview for theoretical and philosophical psychology." Journal of Theoretical and Philosophical Psychology 39.4 (2019): 202.

Tackett, Jennifer L., et al. "Psychology's replication crisis and clinical psychological science." Annual review of clinical psychology 15 (2019): 579-604.