Identifying an extra NMR peak in silyl protection reaction
I believe some of your triisopropylsilyl chloride may be hydrolyzed triisopropylsilylol, $\ce{((CH3)2CH)3SiOH}$. That may gives you $\delta$ 1.04 and 12.4 (for $\ce{C}$ attached to $\ce{Si}$) in $\mathrm{^1H}$- and $\mathrm{^{13}C}$-NMR spectra, respectively. Compare the spectral values in Ref.1 and 2 (see below; corresponding $\ce{^{13}C}$ values are in red):



References:


A. Goti, M. Cacciarini, F. Cardona, A. Brandi, “A convenient access to (3S)-3-(triisopropylsilyl)oxy-1-pyrroline N-oxide, a useful intermediate for polyfunctionalized enantiopure indolizidine and pyrrolizidine synthesis,” Tetrahedron Letters 1999, 40(14), 2853–2856 (https://doi.org/10.1016/S0040-4039(99)00310-X).
R. F. Cunico, L. Bedell, “The triisopropylsilyl group as a hydroxyl-protecting function,” J. Org. Chem. 1980, 45(23), 4797–4798 (https://doi.org/10.1021/jo01311a058).