Specifically recognizes and binds N6-methyladenosine (m6A)-containing RNAs, and regulates their stability (PubMed:28192787). M6A is a modification present at internal sites of mRNAs and some non-coding RNAs and plays a role in mRNA stability and processing (By similarity). Acts as a regulator of mRNA stability by promoting degradation of m6A-containing mRNAs (By similarity). The YTHDF paralogs (ythdf1, ythdf2 and ythdf3) share m6A-containing mRNAs targets and act redundantly to mediate mRNA degradation and cellular differentiation (By similarity). Plays a key role in maternal-to-zygotic transition during early embryonic development, the process during which maternally inherited mRNAs are degraded: acts by binding m6A-containing maternal mRNAs and promoting their degradation (PubMed:28192787). More than one-third of maternal mRNAs can be modified by m6A (PubMed:28192787). Binding to m6A-containing mRNAs results in mRNA degradation (By similarity). Also involved in hematopoietic stem cells specification by binding to m6A-containing mRNAs, such as notch1a, and promote their degradation (PubMed:28869969). The decreased Notch signaling following notch1a degradation promotes endothelial to hematopoietic transition (PubMed:28869969). Promotes formation of phase-separated membraneless compartments, such as P-bodies or stress granules, by undergoing liquid-liquid phase separation upon binding to mRNAs containing multiple m6A-modified residues: polymethylated mRNAs act as a multivalent scaffold for the binding of YTHDF proteins, juxtaposing their disordered regions and thereby leading to phase separation (By similarity). The resulting mRNA-YTHDF complexes then partition into different endogenous phase-separated membraneless compartments, such as P-bodies, stress granules or neuronal RNA granules (By similarity). Localizes to the cytosol and relocates to the nucleus following heat shock stress. Can partition into different structures: into P-bodies in unstressed cells, and into stress granules during stress. Ubiquitously expressed throughout early embryogenesis. The disordered regions have the ability to interact with each other and to 'phase separate' into liquid droplets within the cytosol following binding to mRNAs containing multiple m6A-modified residues. This leads to the partition of m6A-containing mRNAs into membraneless compartments, where mRNAs may be stored, degraded or used to transport mRNAs to dendritic arbors in neurons. Homozygous mutants from the first generation do not show any visible phenotype. Crossing homozygotes mutants together leads to lethality in around 70% of their progeny, because embryos do not developed past the one-cell stage. This lethality is probably mediated by defective sperm males. Defects are due to impaired decay of N6-methyladenosine (m6A)-modified maternal mRNAs, leading to impede zygotic genome activation. Embryos fail to initiate timely maternal-to-zygotic, undergo cell-cycle pause and remain developmentally delayed. Belongs to the YTHDF family. YTHDF2 subfamily.