Context. Abell 1033 is a merging galaxy cluster of moderate mass (M 500 = 3.24 × 10 14 M ) which hosts a broad variety of diffuse radio sources linked to different astrophysical phenomena. The most peculiar one is an ultra-steep spectrum elongated feature which is the prototype of the category of gently re-energized tails (GReET). Furthermore, the cluster hosts sources previously classified as a radio phoenix and a radio halo. Aims. In this work, we aim to improve the understanding of the cosmic ray acceleration mechanisms in galaxy clusters in a frequency and mass range poorly explored so far. Methods. To investigate the ultra-steep synchrotron emission in the cluster, we perform a full direction-dependent calibration of a LOFAR observation centered at 54 MHz. We analyze this observation together with re-calibrated data of the LOFAR Two-meter Sky Survey at 144 MHz and an archival GMRT observation at 323 MHz. We perform a spectral study of the radio galaxy tail connected to the GReET to test if the current interpretation of the source is in agreement with observational evidence below 100 MHz. Additionally, we employ a Markov chain Monte Carlo code to fit the halo surface-brightness profile at different frequencies. Results. We report an extreme spectral curvature for the GReET, the spectral index flattens from α 323MHz 144MHz ≈ −4 to α 144MHz 54MHz ≈ −2. This indicates the presence of a cut-off in the electron energy spectrum. At the cluster center, we detect the radio halo at 54, 144 and at lower significance at 323 MHz. We categorize it as an ultra-steep spectrum radio halo with a low-frequency spectral index α = −1.65 ± 0.17. Additionally, with a radio power of P 150 MHz = 1.22 ± 0.13 × 10 25 W Hz −1 , it is found to be significantly above the radio power-to-cluster mass correlations reported in the literature. Furthermore, the synchrotron spectrum of the halo is found to further steepen between 144 and 323 MHz, in agreement with the presence of a break in the electron spectrum, which is a prediction of homogeneous re-acceleration models.